Capacitive Fold Angle Detection for Foldable Devices
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Solution Overview
Problem
Conventional foldable devices fail to accurately detect the fold angle due to temperature sensitivity and display noise issues, requiring additional sensors like gyroscopic and IR sensors, which increase complexity and costs.
Innovation Solution
A system utilizing a capacitive sensor array to determine the fold angle by obtaining transcapacitance and absolute capacitance measurements, canceling out interference from input objects, and using baseline reference measurements to calculate the fold angle without the need for dedicated sensors like gyroscopic or IR sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated gyroscopic sensors and accelerometers are used to detect fold angle, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The capacitive sensor array originally designed for touch detection is made to serve dual purposes: both touch input detection and fold angle measurement. By processing capacitance changes from electrodes near the hinge, the system achieves fold angle detection without requiring separate dedicated sensors, thus reducing device complexity while maintaining measurement capability.
Solution Approach 2:
The existing capacitive sensor array serves itself by providing additional functionality. The same electrodes and processing circuitry that detect touch inputs also detect fold angle changes through capacitance variations caused by hinge movement, eliminating the need for separate measurement systems.
2Measurement precision
If dedicated IR sensors or Hall sensors are used to detect device closure, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The capacitive sensor array is extended to detect device closure state by monitoring capacitance changes from electrodes positioned near the hinge. This allows the same sensor system to determine both touch inputs and closure status, eliminating the need for separate IR or Hall sensors.
Solution Approach 2:
The capacitive sensing system automatically provides closure detection capability as part of its normal operation, using the natural capacitance changes that occur when the device folds or closes without requiring additional dedicated closure detection hardware.
3Device complexity
If capacitive sensors are used to detect fold angle, then device complexity is reduced, but measurement precision deteriorates due to temperature sensitivity and display noise
Solution Approach 1:
The capacitive sensor array is segmented into different functional zones: touch detection regions and fold angle detection regions near the hinge. By selectively processing signals from specific electrode segments near the hinge, the system isolates fold angle measurement data from general touch detection, improving measurement precision for the specific function.
Solution Approach 2:
The system continuously monitors capacitance changes and uses feedback processing to distinguish between capacitance variations caused by touch inputs and those caused by hinge movement. This feedback mechanism allows the system to filter out noise and temperature effects, maintaining measurement precision while using only capacitive sensors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides accurate and timely fold angle detection, reducing material costs, assembly labor, and simplifying design while avoiding display interference, thereby enhancing reliability and eliminating the need for additional sensors.
Implementation Method 1
Capacitive detection of fold angle for foldable devices
Data Source
AI summary
A system for determining a fold angle of a foldable device, the system including a plurality of electrodes and a processing system, wherein the processing system is configured to obtain transcapacitance measurements via a subset of the plurality of electrodes; obtain absolute capacitance measurements via the subset of the plurality of electrodes; and determine the fold angle of the foldable device based on the transcapacitance measurements and the absolute capacitance measurements.